Thiopurine S-methyltransferase pseudogene 1 (TPMTP1)

Thiopurine S-methyltransferase pseudogene 1 (TPMTP1) is a pseudogene located on human chromosome 18q, closely related by sequence to the true thiopurine S-methyltransferase (TPMT) gene[2]. Pseudogenes like TPMTP1 do not encode a functional enzyme or protein product and are not involved in substrate metabolism, drug interaction, or disease processes. In contrast, the functional TPMT is responsible for the metabolism of thiopurine drugs and is a clinically relevant pharmacogene[2][6][8]. However, TPMTP1 itself does not serve as a therapeutic target, nor is it implicated in disease or pharmacological intervention. The presence of "pseudogene" in its designation indicates its lack of protein-coding capacity and biological function. *Note*: Queries about TPMTP1 as a therapeutic target are likely based on confusion with TPMT. Only TPMT (not TPMTP1) is biomedically significant as an enzyme with drug interactions and genetic variation impacting clinical care[2][6][8].

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